With the recognition that UV light adversely affects the skin, make-up cosmetics with UV protection effect have also been developed, which comprise UV scatterers such as fine particulate titanium dioxide or fine particulate zinc oxide and/or organic UV absorbers. In recent years, there has been an increasing demand for cosmetics with high UV protection effect. In response to such a demand, it is usual to incorporate a high content of UV scatterers and/or UV absorbers. However, such a high content of UV scatterers (e.g., fine particulate titanium dioxide) in cosmetics leaves graininess on the skin or creates a thick cosmetic film, thereby resulting in an unnatural finish. On the other hand, such a high content of UV absorbers has a problem in safety, and in fact, it is not possible to use a high content of UV absorbers because there is a limit on their content to be incorporated. For these reasons, there is a strong demand for the development of a UV scatterer, particularly titanium dioxide, which has a high level of UV protection ability sufficient to ensure UV protection even at a low content.
Under these circumstances, the inventors of the present invention have proposed fan-shaped titanium dioxide composed of aggregated primary particles of needle-like titanium dioxide in Japanese Patent Public Disclosure No. H10-245228 (Patent Document 1). Since these particles were synthesized by the wet method to have a larger particle size, they had adequate hiding power and tinting strength, and also showed improved UV blocking ability, but not to satisfaction.
On the other hand, fine particulate-type titanium dioxide of 100 nm or less has been known as an external additive for toner since a long time ago. Although this type of titanium dioxide is excellent in imparting fluidity and controlling toner charge, it is feared that it would be embedded in the toner particle surface due to its small size, and therefore, it is not necessarily preferred for use as spacer particles for toner.